Höcker, B.; Lechner, H.

ChemBioChem 2021, 22, 1573-1577, 10.1002/cbic.202000880

An artificial cofactor based on an organocatalyst embedded in a protein has been used to conduct the Baylis-Hillman reaction in a buffered system. As protein host, we chose streptavidin, as it can be easily crystallized and thereby supports the design process. The protein host around the cofactor was rationally designed on the basis of high-resolution crystal structures obtained after each variation of the amino acid sequence. Additionally, DFT-calculated intermediates and transition states were used to rationalize the observed activity. Finally, repeated cycles of structure determination and redesign led to a system with an up to one order of magnitude increase in activity over the bare cofactor and to the most active proteinogenic catalyst for the Baylis-Hillman reaction known today.

Gao, X.; Zhao, L.

Sci. Adv. 2020, 6, 10.1126/sciadv.abb1421

Metalloenzymes are promising anticancer candidates to overcome chemoresistance by involving unique mechanisms. To date, it is still a great challenge to obtain synthetic metalloenzymes with persistent catalytic performance for cancer-specific DNA cleavage and operando imaging. Here, an artificial metalloenzyme, copper cluster firmly anchored in bovine serum albumin conjugated with tumor-targeting peptide, is exquisitely constructed. It is capable of persistently transforming hydrogen peroxide in tumor microenvironment to hydroxyl radical and oxygen in a catalytic manner. The stable catalysis recycling stems from the electron transfer between copper cluster and substrate with well-matched energy levels. Notably, their high biocompatibility, tumor-specific recognition, and persistent catalytic performance ensure the substantial anticancer efficacy by triggering DNA damage. Meanwhile, by coupling with enzyme-like reactions, the operando therapy effect is expediently traced by chemiluminescence signal with high sensitivity and sustainability. It provides new insights into synthesizing biocompatible metalloenzymes on demand to visually monitor and efficiently combat specific cancers.

Lewis, J.C.; Roux, B.

Angew. Chem. Int. Ed. 2021, 60, 23672-23677, 10.1002/anie.202107982

Artificial metalloenzymes (ArMs) are commonly used to control the stereoselectivity of catalytic reactions, but controlling chemoselectivity remains challenging. In this study, we engineer a dirhodium ArM to catalyze diazo cross-coupling to form an alkene that, in a one-pot cascade reaction, is reduced to an alkane with high enantioselectivity (typically >99 % ee) by an alkene reductase. The numerous protein and small molecule components required for the cascade reaction had minimal effect on ArM catalysis. Directed evolution of the ArM led to improved yields and E/Z selectivities for a variety of substrates, which translated to cascade reaction yields. MD simulations of ArM variants were used to understand the structural role of the cofactor on ArM conformational dynamics. These results highlight the ability of ArMs to control both catalyst stereoselectivity and chemoselectivity to enable reactions in complex media that would otherwise lead to undesired side reactions.

Dervan, P.B.

Science 1987, 238, 1129-1132, 10.1126/science.3120311

A synthetic 52-residue peptide based on the sequence-specific DNA-binding domain of Hin recombinase (139-190) has been equipped with ethylenediaminetetraacetic acid (EDTA) at the amino terminus. In the presence of Fe(II), this synthetic EDTA-peptide cleaves DNA at Hin recombination sites. The cleavage data reveal that the amino terminus of Hin(139-190) is bound in the minor groove of DNA near the symmetry axis of Hin recombination sites. This work demonstrates the construction of a hybrid peptide combining two functional domains: sequence-specific DNA binding and DNA cleavage.